Recently, cultivating plants by use of an artificial light source has been keenly studied. Attention has been paid particularly to a method of cultivating plants by illuminating the plants with light of a light emitting device (such as a light emitting diode (LED)) which (i) excels in monochromaticity, (ii) saves energy, (iii) has a long life duration, and (iv) can be downsized.
Patent Literature 1 cited below discloses a plant growing device as an example of a conventional light emitting device which can be used in a factory etc. where living organisms are grown, for example, living organisms are cultivated or cultured.
A plant growing device 100 (see FIG. 10), disclosed in Patent Literature 1, includes (i) a light emitting section 110 for emitting light which is used to grow a plant, (ii) an electric power supplying section 120 for supplying electric power to the light emitting section 110 so that the light emitting section 110 can emit light whose spectrum is changeable, (iii) a determining section 131 for determining kinds of plant 101 to be grown, and (iv) a growth light setting section 132 for setting a spectrum of light by controlling the electric power supplying section 120 in accordance with the kinds of plant 101 which has been determined by the determining section 131.
The light emitting section 110 includes a substrate 111 in a plate shape (see FIG. 11). The substrate 111 has a surface on which various LEDs 112 for emitting light of different spectra are arranged (see FIG. 11). The plant 101 is irradiated with light emitted from the LEDs 112 (see FIG. 10). Each of the LEDs 112 is, for example, in a bullet shape.
Patent Literature 2 cited below discloses (i) an LED light source for plant cultivation and (ii) a plant cultivating vessel with which an LED light source is to be individually combined. Specifically, red LEDs 210 and blue LEDs 220 are provided on one (1) printed board (10 cm×10 cm, thickness: 1.6 mm), and the printed board are combined with a lid 200 (11 cm×11 cm, height: 17 mm) of the plant cultivating vessel (see FIG. 12). The lid 200 itself serves as a light source. The plant cultivating vessel is constituted by (i) a plastic frame 240 and (ii) an air-permeable and transparent resin film 230 (see FIG. 13). A rock wool culture medium 250 is provided in the plant cultivating vessel (see FIG. 13). The lid 200 is fixed to the plastic frame 240 by a fixing lever 260.